Update README with instructions on running tests with coverage.
Update README with instructions on running tests with coverage.

whitzhu/kolibri,benjaoming/kolibri,66eli77/kolibri,aronasorman/kolibri,learningequality/kolibri,aronasorman/kolibri,lyw07/kolibri,MingDai/kolibri,whitzhu/kolibri,MCGallaspy/kolibri,DXCanas/kolibri,jonboiser/kolibri,66eli77/kolibri,jayoshih/kolibri,rtibbles/kolibri,aronasorman/kolibri,mrpau/kolibri,MCGallaspy/kolibri,DXCanas/kolibri,jonboiser/kolibri,66eli77/kolibri,rtibbles/kolibri,indirectlylit/kolibri,DXCanas/kolibri,lyw07/kolibri,jayoshih/kolibri,benjaoming/kolibri,jamalex/kolibri,benjaoming/kolibri,jayoshih/kolibri,learningequality/kolibri,indirectlylit/kolibri,mrpau/kolibri,jamalex/kolibri,rtibbles/kolibri,indirectlylit/kolibri,jtamiace/kolibri,jamalex/kolibri,aronasorman/kolibri,christianmemije/kolibri,whitzhu/kolibri,lyw07/kolibri,whitzhu/kolibri,MingDai/kolibri,indirectlylit/kolibri,learningequality/kolibri,jonboiser/kolibri,rtibbles/kolibri,ralphiee22/kolibri,jayoshih/kolibri,benjaoming/kolibri,ralphiee22/kolibri,jonboiser/kolibri,jtamiace/kolibri,jtamiace/kolibri,mrpau/kolibri,christianmemije/kolibri,mrpau/kolibri,66eli77/kolibri,ralphiee22/kolibri,lyw07/kolibri,MCGallaspy/kolibri,learningequality/kolibri,jamalex/kolibri,jtamiace/kolibri,MingDai/kolibri,DXCanas/kolibri,christianmemije/kolibri,christianmemije/kolibri,ralphiee22/kolibri,MingDai/kolibri